A post-vasectomy sperm granuloma is a small (usually less than 1 cm) lump or nodule that forms at the site where the vas deferens was cut during a vasectomy. It occurs when sperm leaks out of the vas deferens into the surrounding tissue, triggering an inflammatory response. The body then encapsulates the leaked sperm, forming a granuloma. They appear sometime between a few days and several months after a vasectomy. 

They usually go unnoticed, but they occasionally cause discomfort.  If it causes discomfort, 7-10 days of an anti-inflammatory medication, like ibuprofen, is recommended.  The recommended dosage is 400-600 mg (2-3 over-the-counter tabletes) 3 times daily. It is better to take the ibuprofen with food so it doesn’t upset your stomach.  

These lumps may take several months to resolve completely, but the discomfort should resolve with and after taking the anti-inflammatory.  

Following is an excellent video on sperm granulomas done by vasectomy colleague, Dr. Esgar Guarin.